1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing pastries and, more particularly, to a method and apparatus for manufacturing Korean traditional oil pastries, mechanized by means of an extruder and a conveyor unit and thus being suitable for mass production of such pastries.
2. Description of the Related Art
As well known to those skilled in the art, Korean traditional oil pastries are produced by frying uncoated, sized pieces made of a main material of glutinous rice, the pastries having unique texture and taste. In a more detailed description, the pastries are produced by immersing glutinous rice in water to moisturize the rice, grinding the moisturized glutinous rice, mixing the ground glutinous rice with sub-materials to prepare mixed materials, and kneading, steaming, aerating and drying the materials prior to forming the uncoated and sized pieces. Thereafter, the pieces are fried and coated with a coating material, such as popped rice.
Such a conventional pastries are generally used for ceremonial occasions in the past, whereas the pastries are now normally used as gifts and snack foods in Korea and occasionally eaten by foreigners.
The conventional method of manufacturing Korean traditional oil pastries consists of a gelatinization step, an immersing step, a grinding step, a water content regulation step, a steaming step, and an aeration step. The aeration step is to uniformly distribute air in a steamed dough by beating the dough so as to destroy the texture of gelatinized dough. Such a conventional method of manufacturing Korean traditional oil pastries suffers from a number of problems as follows.
In such a conventional method, the aeration step has to be manually carried out by hand, that is, by beating the dough with a wooden roller by hand, and reiterated several tens of times. Since the aeration step has to be manually performed, the yield depends on the worker's individual ability and even a skilled worker may not produce a large yield in a short period.
After the aeration step is completed, the aerated dough is spread on a wheat flour covered floor and cut into uncoated and sized pieces. The pieces are dried on the hot floor for a day and fried in oil to be swelled. To be swelled means that the volumes of the individual pieces are enlarged because flexible starchy membranes become porous structures.
The enlargement of the volume is due to the facts that expansion of air and expansive pressure resulting from vaporization of water occur and simultaneously hydrogen bonds are broken between amylopectin chains. The softness of the pastries depends on the swelling. Such a conventional method is also problematic in that the degree of swelling depends on weather and worker's skill.